This invention relates to a liquid purification apparatus and relates particularly, though not exclusively, to a liquid purification apparatus for purifying water and other liquids by the well-known process of oxidization purification using the sterilizing effects of oxygen radical (Oxe2x88x92).
As is well known, the combination of H2O2 and silver/copper makes an efficient biocide. When either H2O2, or a solid peroxygen compound that produces H2O2, is simultaneously added to minute amounts of silver, a catalytic reaction occurs increasing the efficiency of the H2O2 or the silver often used as a biocide. As a result, this process can be used to sterilize drinking water or water that may be in contact with humans, such as water in pools, spas and the like.
Various attempts have been made in the past to devise apparatus and methods for the effective use of H2O2 in solid form. However for a number of reasons success has not been attained. In consequence, no effective technology is currently available, due mainly to difficulties in the dissolution process and in controlling the dosages required. Many prior proposals have involved usage systems requiring labor intensive packaging in an endeavor to achieve accurate levels of one or more of three additives, namely Ag+, copper and H2O2. For example, U.S. specification Pat. No. 2,105,9835 of Krause prescribed individual packaging, using tablet form, enclosed in soluble wrappings which gradually dissolve encased in soluble crystals, powder mixes, adding to ice, and so forth. Likewise, United Kingdom Patent No. 432101 of Katadyn AG, discloses the use of packets, tablets, pills, capsules or ampoules, soluble coating of crystals or gelatine. Thus, in the prior art, the dosing of metals and H2O2 involves cumbersome procedures and apparatus, with the apparatus also being expensive to manufacture, and in the main only specific predetermined bodies of water can be treated.
Other problems with the prior art arises from the fact that the handling of solid peroxide compounds is hazardous and the difficulty in releasing a controlled dosage of oxygen radical over an extended period of time.
It is an object of the present invention to provide apparatus which will ameliorate at least some of the problems associated with the prior proposals by effectively controlling the release of H2O2 from a solid compound to allow the production of a diluted solution of a material which may be used available for catalyzation with the previously mentioned metals to produce the oxygen radical in a manner achieving both safety and increased efficiency of operation.
A further object of the invention is to provide apparatus of the type just described which will allow effective control of the dosing of oxygen radicals within an in-line flow passage for the water (or liquid), regardless of the volume being passed, or the actual flow rate, and regardless of contamination present which will require nil external energy or apparatus for dosing.
Yet another object of the invention is to provide such apparatus and usage methods which will ensure that the opportunity of the solid peroxide compounds to come into contact with the user will be eliminated, while at the same time the dosing system will allow the introduction of the oxidizing material while avoiding wastage of any products involved.
Other objects and advantages will be hereinafter apparent, such as providing advantages over the prior art in that the apparatus will not be subject to operation difficulties in areas where temperature variations may be extreme as the unit will be encompassed by the liquid to be treated.
With these and other objects in view the present invention provides a liquid purification apparatus including a main body having means to allow liquid to enter said main body, an exit means to allow exit of liquid from said main body, a solid compound located within said main body for dissolution by said liquid and means cooperating with said solid compound to expose a substantially constant surface area of said compound to said liquid.
Preferably said main body and said cooperating means is shaped to provide a tortuous path for flow of liquid before contact with said compound is made. Preferably said substantially constant surface area is planar. In a preferred embodiment said solid compound is located in a tubular container sealed at one end and having an opening into said tubular container at the other end. In a further practical embodiment said solid compound is located in a tubular container sealed at one end and having a perforated piston abutting the solid compound whereby said piston remains in contact with said solid compound as said solid compound dissolves. Preferably the length/height of the tubular container is greater than twice the effective diameter of the surface area exposed directly to liquid.